NCT06030726

Brief Summary

In randomized clinical trials and observational studies, influenza vaccination has been shown to be effective in reducing influenza-related illness, hospitalizations, cardiovascular events, and mortality in select populations. However, the real-world effectiveness of influenza vaccination is limited by its uptake. Conducted during the 2022/2023 influenza season, the first NUDGE-FLU trial demonstrated the effectiveness of two electronic behavioral nudging letter strategies in increasing influenza vaccination rates among older adults in Denmark - a letter highlighting potential cardiovascular benefits of vaccination and a standard informational letter sent at baseline and repeated at day 14. This present study will once again investigate whether digital behavioral nudges delivered via the official, mandatory Danish electronic letter system can increase influenza vaccine uptake among older adults including whether the effectiveness of previously successful strategies can be confirmed during a subsequent influenza season.

Trial Health

87
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
881,373

participants targeted

Target at P75+ for not_applicable

Timeline
Completed

Started Sep 2023

Shorter than P25 for not_applicable

Geographic Reach
1 country

1 active site

Status
completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

First Submitted

Initial submission to the registry

August 31, 2023

Completed
11 days until next milestone

First Posted

Study publicly available on registry

September 11, 2023

Completed
3 days until next milestone

Study Start

First participant enrolled

September 14, 2023

Completed
4 months until next milestone

Primary Completion

Last participant's last visit for primary outcome

January 1, 2024

Completed
5 months until next milestone

Study Completion

Last participant's last visit for all outcomes

May 31, 2024

Completed
Last Updated

October 10, 2024

Status Verified

October 1, 2024

Enrollment Period

4 months

First QC Date

August 31, 2023

Last Update Submit

October 8, 2024

Conditions

InfluenzaBehavior and Behavior Mechanisms

Keywords

InfluenzaVaccinationNudgingBehavioral Science

Outcome Measures

Primary Outcomes (1)

  • Number of participants who received an influenza vaccine

    Up to 3 months

Secondary Outcomes (1)

  • Time from intervention delivery to influenza vaccination

    Up to 3 months

Other Outcomes (25)

  • Number of participants with laboratory-confirmed influenza

    Up to 8 months

  • Number of participants with a hospitalization for influenza or pneumonia

    Up to 8 months

  • Number of participants with a hospitalization for any respiratory disease

    Up to 8 months

  • +22 more other outcomes

Study Arms (7)

Usual Care

NO INTERVENTION

No letter

Standard Letter

EXPERIMENTAL

This group will receive a standard letter on the benefits of influenza vaccination without behavioral economic enhancement

Behavioral: Behavioral Economic Principles

Repeated Letter

EXPERIMENTAL

The standard letter sent out two times instead of once

Behavioral: Behavioral Economic Principles

Cardiovascular Gain-Framing Letter

EXPERIMENTAL

Text added to the standard letter highlighting potential cardiovascular benefits of influenza vaccination

Behavioral: Behavioral Economic Principles

Respiratory Gain-Framing Letter

EXPERIMENTAL

Text added to the standard letter highlighting potential respiratory disease-related benefits of influenza vaccination

Behavioral: Behavioral Economic Principles

Implementation Intention Prompt Letter

EXPERIMENTAL

Implementation intention prompt added to the standard letter

Behavioral: Behavioral Economic Principles

Loss-Framing Letter

EXPERIMENTAL

Text added to the standard letter highlighting potential risks of not receiving influenza vaccination

Behavioral: Behavioral Economic Principles

Interventions

Behavioral Economic PrinciplesBEHAVIORAL

The control arm will receive no letter to reflect the background vaccination uptake. Intervention arms will test the effects of different letters developed using behavioral economic principles.

Cardiovascular Gain-Framing LetterImplementation Intention Prompt LetterLoss-Framing LetterRepeated LetterRespiratory Gain-Framing LetterStandard Letter

Eligibility Criteria

Age65 Years+
Sexall
Healthy VolunteersYes
Age GroupsOlder Adult (65+)

You may qualify if:

  • Age \>=65 years at January 15, 2024 (eligible for free-of-charge influenza vaccination in the Danish public health system)
  • Access to the official, mandatory Danish electronic mailbox system

You may not qualify if:

  • Persons living in nursing homes (approximated as any person living at an address with \>=6 inhabitants aged 80 years and above)
  • Known to have already scheduled influenza vaccination appointment

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte

Hellerup, Capital Region, 2900, Denmark

Location

Related Publications (3)

  • Bhatt AS, Johansen ND, Vaduganathan M, Modin D, Pareek M, Chatur S, Claggett BL, Janstrup KH, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Dueger EL, Samson S, Loiacono MM, Harris RC, Kober L, Solomon SD, Martel CJ, Sivapalan P, Jensen JUS, Biering-Sorensen T. Electronic Nudges and Influenza Vaccination Among Patients With a History of Myocardial Infarction: Insights From 3 Nationwide Randomized Clinical Trials. JAMA Cardiol. 2025 Jan 1;10(1):78-86. doi: 10.1001/jamacardio.2024.4648.

    PMID: 39550717DERIVED

  • Johansen ND, Vaduganathan M, Bhatt AS, Modin D, Chatur S, Claggett BL, Janstrup KH, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Kober L, Solomon SD, Sivapalan P, Jensen JUS, Martel CJ, Krause TG, Biering-Sorensen T. Electronic nudges for sustained influenza vaccination uptake in older adults: the nationwide randomized NUDGE-FLU-2 trial. Nat Med. 2024 Nov;30(11):3142-3149. doi: 10.1038/s41591-024-03202-4. Epub 2024 Aug 30.

    PMID: 39215149DERIVED

  • Johansen ND, Vaduganathan M, Bhatt AS, Modin D, Chatur S, Claggett BL, Janstrup KH, Larsen CS, Larsen L, Wiese L, Dalager-Pedersen M, Kober L, Solomon SD, Sivapalan P, Jensen JUS, Martel CJ, Krause TG, Biering-Sorensen T. Rationale and design of NUDGE-FLU-CHRONIC and NUDGE-FLU-2: Two nationwide randomized trials of electronic nudges to increase influenza vaccination among patients with chronic diseases and older adults during the 2023/2024 influenza season. Am Heart J. 2024 Jun;272:23-36. doi: 10.1016/j.ahj.2024.03.003. Epub 2024 Mar 7.

    PMID: 38460754DERIVED

MeSH Terms

Conditions

Influenza, HumanBehavior

Condition Hierarchy (Ancestors)

Respiratory Tract InfectionsInfectionsOrthomyxoviridae InfectionsRNA Virus InfectionsVirus DiseasesRespiratory Tract Diseases

Study Officials

  • Tor Biering-Sørensen, MD, MSc, MPH, PhD

    Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte

    PRINCIPAL INVESTIGATOR

Study Design

Study Type
interventional
Phase
not applicable
Allocation
RANDOMIZED
Masking
NONE
Purpose
OTHER
Intervention Model
PARALLEL
Sponsor Type
OTHER
Responsible Party
SPONSOR INVESTIGATOR
PI Title
Professor, MD, MSc, MPH, PhD

Study Record Dates

First Submitted

August 31, 2023

First Posted

September 11, 2023

Study Start

September 14, 2023

Primary Completion

January 1, 2024

Study Completion

May 31, 2024

Last Updated

October 10, 2024

Record last verified: 2024-10

Data Sharing

IPD Sharing
Will share

Data will be collected from Danish administrative health registries, which are subject to Danish legislation and can only be made available to a third party under certain conditions. Please contact the sponsor-investigator in case of any inquiries.

Locations

DK(1)